Structured column packing has been known for many years for use in a distillation column for the rectification of a fluid mixture. Early forms of structured packing included Stedman packing, described in U.S. Pat. No. 2,047,444. In general, structured packing refers to packing wherein individual members have a specific orientation relative to each other and to the column axis.
Recent advances in structured packing include the development of structured packing made from thin sheets of corrugated material. Generally the material is metal. This structured packing is made by corrugating the thin sheets so that the corrugations form diagonally on the sheets. The packing is employed in a column with the sheets in a vertical orientation so that the corrugations are at an angle to the column axis.
An improvement in corrugated structured packing is the texturization of the packing sheet surface. The texturization improves the uniform spreading of liquid over the packing surface thus improving the vapor-liquid contact and thus the mass transfer within the column. Many different kinds of texturizations are known such as fluting, lancing or embossing the sheet surface. Other texturization techniques include perforating the sheet to leave protuberances around the holes and perforating the sheet to leave burrs around the holes.
While commercially available texturized corrugated structured packing has been shown to achieve good results, it has sometimes resulted in poor performance in some situations such as under turndown conditions. For example, it has been observed that liquid tends to flow in the corners of the corrugations which is detrimental to the performance of the packing. This requires removing or disrupting the accumulated liquid running in the corners or suffer with degraded performance. Thus it is desirable to have texturized corrugated structured packing which performs well under all distillation conditions including turndown.
Accordingly it is an object of this invention to provide improved texturized corrugated structured packing which can perform well under all distillation conditions including turndown.
It is another object of this invention to provide a distillation method which can be carried out effectively under all distillation conditions including turndown and which employs texturized corrugated structured packing as vapor-liquid contact elements for the distillation.